Overview
This was a ground test of the Hermes Pathfinder rocket. It occurred on Field A at 3:45 PM on November 10, 2017. It was the first use of the Pyrotechnic Piston to separate the rocket. The piston contained 1g of 4F black powder. The tender descender contained .2g of black powder. The shear pins used were not document but were likely 2x 6-32 nylon pins and 1x 4-40 nylon pin. The rocket successfully separated, and the tender descender released the main parachute appropriately. After de-integration it was found that the Avionics Bulkhead was seriously deformed. This prevented the planned flight on November 11, 2017 from occurring.
Failure Investigation
Solidworks FEA confirmed that the deformation is consistent with a 2-bolt load application.
To perform this analysis, we performed a static load analysis on the Avionics Bulkhead modeled in CAD as of November 16, 2017. Some notable limitations of this analysis are:
- In actuality, this would be better modeled by an impact.
- Since significant deformation was observed (see the image below), it is clear that a nonlinear analysis would be required to accurately model the deformation. The static load analysis was performed to get a basic idea of expected deformation shape and to prove material exceedance at the expected loads.
Additional Analysis is underway.